Hi, I'm planning on upgrading our Exchange organization to 2007 in April. My initial plan was to get the message routing side done the first weekend (i.e after Forest/AD prep, install CAS and HUb roles) and keep our back end mailbox servers as 2003. I was told that there were performance issues related to having a pure 2003 back end in a 2007 organization? Is this true? If so, what is the issue?

Dear RichCarey, You can deploy Microsoft Exchange Server 2007 in an existing Exchange Server 2003 or Exchange 2000 Server organization that is operating in native mode. Coexistence with these two Exchange versions is supported. The existing organization can contain Exchange 2003 servers, Exchange 2000 servers, or both versions. There are many important differences between Exchange 2003 or Exchange 2000 and Exchange 2007 in how the servers are administered and in how server-to-server communication occurs. This topic provides an overview of the planning considerations and configuration steps that you must take when Exchange 2007 will coexist with earlier versions of Exchange. There are many differences between Exchange 2003 and Exchange 2007. Also, I didnt see any document about there were performance issues when having a pure Exchange 2003 back end in an Exchange 2007 organization. Please let me know where did you get the information. For more information about them, please refer to the following article: Planning for Coexistence http://technet.microsoft.com/en-us/library/aa998186.aspx Coexisting with Exchange Server 2003 and Exchange 2000 Server: http://technet.microsoft.com/en-us/library/aa998604.aspx I look forward to hearing from you.Regards, Rock Wang - MSFT

I was told from a consultant who was helping upgrade the VOIP management software that he had some clients with all 2003 back-end servers who were experiencing performance issues.I'm betting it was due to missed steps when they implemented the Exchange 2007 upgrade. Possibly, link state not being suppressed or some routing group issues.I just wanted to be sure there weren't any known issues.Thanks.

Hi RichCarey, Based on my research, I didnt found any known issue by now. If I would find it, I will update the post. There could be many reasons why he encounter performance issue. Microsoft Exchange performance is affected by many factors such as user profiles, system architecture, software, and hardware components. Make sure that Windows is functioning correctly because, if it is not, your Exchange performance will be affected. Monitoring server performance helps to make sure that your servers are functioning correctly and helps you identify bottlenecks in the system. You can use the performance monitoring data to identify problems and apply corrective action. You can also use the monitoring data to enhance the performance of your servers by identifying areas that need additional resources. For example, you may need to increase your storage capacity to handle the growing number of users in your organization. For more information about Server Performance, please refer to the following article: Monitoring Server Performance http://technet.microsoft.com/en-us/library/bb266984.aspx If anything is unclear, feel free to let me know. I look forward to hearing from you. Regards, Rock Wang - MSFT